Pitch control for aircraft



Aug. 9, 1966 H. L. M PHERSON PITCH CONTROL FOR AIRCRAFT Original FiledMay 12, 1962 5 SheetsSheet 1 INVENTOR, v Hurry L. McPherson BY Mfl 1966H. L. M PHERSON PITCH CONTROL FOR AIRCRAFT 5 Sheets-Sheet 2 OriginalFiled May 12, 1962 FIC5.5

INVENTOR, Hurry L. McPherson Aug. 9, 1966 H. M PHERSON PITCH CONTROL FORAIRCRAFT Driginal Filed May 12 1962 v 5 Sheets-Sheet 5 FIG. 8

FIG. 7

FI G, IO

FIG.-9

, INVENTOR, Hurry L. McPherson a BY l United States Patent 3,265,335PiTCH (IONTRGL FOR CRAFT Harry L. Mciherson, 1125 Poppen Drive, Memphis,Tenn. Continuation of application Ser. No. 187,021, Apr. 12, 1962. Thisapplication Aug. 13, 1964, Ser. No. 392,070 11 filaims. (Cl. 24479) Thisinvention relates to certain new and useful improvements in means forcontrolling aircraft flight, and particularly relates to means forcontrolling and correcting pitch of aircraft in which the aircraftdeviates from straight and level flight to an attitude of incline or anattitude of decline.

This application is a continuation of application Serial Number 187,021,filed Apr. 12, 1962, now abandoned.

Many attempts have heretofore been made to automatically control andadjust variations in the pitch attitude of aircraft. Many of the priorattempts at such controls have required involved, expensive anddifficult installations for accomplishing the purpose, have often provenineffective from a commercial point of view, and have otherwise not beenfully accepted, particularly in connection with small aircraft, onaccount of the expense of installation and the sometime uncertainty ofaction involved.

Other attempts have been made involving the utilization of a gyroscopepurportedly coupled to control surfaces of the aircraft ostensibly forthe same purpose. However, such employment of a gyroscope without otherfeatures such as comprise important features of the present inventiondoes not accomplish the entire result desired, since the gyroscope iscapable only of curing curvature in flight path such as leads toward thechange of pitch attitude of the aircraft, but has no means involvedtherein for returning the aircraft to level flight attitude.

The present invention is directed toward the utilization of a gyroscopein connection with a rotatable operational means coupled to thegyroscope and operable by change of attitude through precession of thegyroscope under the torque exerted by a pitch curvature in line offlight resulting in a change of attitude of the aircraft, together withmeans unbalancing the gyroscope in altered flight attitude so as furtherto require the controls to be returned not only to straight uncurvcdflight, but also to flight which is level with the path desired.

In order to accomplish this purpose the present invention provides forcoupling the gimbal ring by which the gyroscope is supported to arotatable operational element so that upon torque force being appliedthrough change in pitch attitude of the aircraft the precession of thegyroscope will effect rotation of the gimbal about its supporting axis,causing a rotation of the operational means and consequently effecting amanipulation of the control surfaces of the aircraft to which the deviceis connected. Additionally the gyroscope, including a balance disc, isprovided with a weighted member which, so long as the aircraft and thegyroscope are in normal attitude, does not disturb the balance of thegyroscope and gimbal, but when the attitude of the aircraft and of thegyroscope has been changed in undesired manner the force of gravity actsupon the weight so as to effect an unbalance of the gyroscopicarrangement and to require a cooperation between the gyroscopic-gimbaleffect returning the aircraft to straight flight and the unbalanceeffect urging the return of the aircraft to level flight along thedesired path.

The principal object of the present invention is to provide a simplegyroscopic device together with unbalance means coupled throughrotatable means with control surfaces of the aircraft in order to effectautomatic correction of undesired changes in pitch attitude of theaircraft.

A further object of the invention is to provide such a Patented August9, 1965 device in which the rotor of the gyroscope is revolved upon anaxis normally parallel with the longitudinal axis of the aircraft,supported by a gimbal ring rotatable upon an axis which is normallyperpendicular to the longitudinal axis of the aircraft, and with thegimbal ring being connected through a balance disc to a rotatable memberby which change in position and alteration in control connection may beeffected.

A further object of the invention is to provide such a device in which aweight is disposed eccentrically of the balance disc so as to beaffected by gravitational force due to change of attitude and positionso as further to assist in the completion of the correction of flightattitude from undesired pitch positions.

A further object of the present invention is to provide such a device inwhich the rotatable operation member comprises a rotatable valve ro-toradapted to effect approprrate communication for operation of the controlsurfaces of the aircraft.

A further object of the present invention is to provide such a device inwhich the rotatable valve means comprises an air valve adapted to effectrespectively communication to vacuum and to atmosphere for the operationof suitable servo units for the operation of control surfaces of theaircraft; and

A further object of the invention is generally to simplify, improve andmake practical the design, construction and efficiency of means forcontrolling the pitch attitude of aircraft.

The means by which the foregoing and other objects of the presentinvention are accomplished and the mannor of their accomplishment willbe readily understood from the following specification upon reference tothe accompanying drawings, in which:

FIG. is a side elevational view of the .device of the present invention,with parts broken away for purposes of illustration, and with otherparts relating to control suilfaces of the aircraft being shown somewhatschematica y. 2 is a top plan View of the device of the presentinvention, with a supporting shelf symbolical of the means by which thedevice may be supported in the aircraft being fragmentairily shown.

FIG. 3 is a vertical sectional view, with certain parts shown inelevation, and other parts broken away for purposes of illustrationtaken as on the line IIIIII of FIG. 2.

*FIG. 4 is an inverted sectional plan view taken as on the lines IV-IVof FIGS. 1 and 3.

FIG. 5 is a sectional plan view taken as on the lines V-V of FIGS. 1 and3.

FIG. 6 is a vertical sectional view, with certain parts shown inelevation, and other parts broken away for purposes of illustrationtaken as on the line VI--VI of FIG. 3.

FIG. 7 is a sectional plan View taken as on the line VllVII of FIG. 3.

FIG. 8 is a fragmentary sectional plan view taken as on the lineVIII-VIII of FIG. 3.

FIG. 9 is a fragmentary sectional plan view taken as on the line IXIX ofFIG. 6; and

FIG. 10 is a view similar to FIG. 9 showing the operational rotor meansin an operated position.

Referring now to the drawings in which the various parts are indicatedby numerals, the means of the present invention comprises a sensingdevice generally indicated at 21, which includes an external casing 23.Casing 23 is provided with an enlarged base 25 which may be mountedsuitably in an aircraft, as by attachment to a shelf 27, and beconnected thereto as by screws 29 extending downwardly through the baseof the case 25.

Housed within casing 23 is a gyro wheel 31 which is mounted for spinningmovement upon a shaft 33, the axis of spinning rotation of the gyrowheel being normally parallel to the longitudinal axis of the aircraft.Gyro shaft 33 is rotatably supported at its opposite ends in a gimbalcage 35, .gimbal cage 35 being supported for pivoting movement by upperand lower pivots 36, 37, which engage bearings 38, 39 in the cage. Uppergimbal pivot 36 is connected to the top of casing 23, while lower gimbalpivot 37 is connected to a bracket 41 which spans across casing '23 andis fixed thereto. The pivot axis of gimbal cage 35 about pivots 36, 37is disposed perpendicular to the longitudinal axis of the aircraft andalso perpendicular to the spin axis of gyro wheel 31.

Fixed to the lower end of gimbal cage 35 above the level of bracket 41is a plate 43 which is thus adapted to turn pursuant to pivotingrotation of the gimbal cage in the operation of the device. Plate 43 ispreferably centrally cut out so as to embrace and not interfere with thelower pivot of the gimbal cage. Toward one side of plate 43 andcentrally offset a post 45 is fixed, to which is connected one end of aspring loaded lever 47, the spring loaded lever being connected to aspring 49 seated against a block 51, block '51 being adjustably mountedon slide pins 53 to adjust the tension and compression of spring 49 foruse purposes, the slide pins 53 being connected to casing 23, and theadjustment of the position of the block seat being effected by anadjustment screw 55 extending through the casing for external access.

Gyro [Wheel 31 is shown as of the air jet driven type and an air nozzleinlet 57 extends into discharge communication with the gyro wheel, withthe air brought into nozzle 57 passing through a suitable air filter 59.

Preferably air flow through nozzle 57 is accomplished through a vacuumoutlet 61 coupled as through a line 63 to a suitable source of vacuum65. In the event that the vacuum source 65 is of a greater capacity thanis desired for drive of the gyro wheel, a damper 67 may be interposed inline 63 between the vacuum source and vacuum outlet 61.

Also connected to plate 43 and extending downwardly therefrom,preferably spaced from post 4-5, is a drive pin 69.

It will be seen that gyro wheel 31, gimbal cage 35, the casing, the airnozzle, and the vacuum source for drawing the .air to drive the gyrowheel, together with plate 43 and drive pin 69, comprise a gyro sensingunit commonly used in a number of present aircraft instruments which arereadily available and easily adapted for use in the present system. Thecoupling of the gyro unit through i the plate and the post to springloaded lever 47 and thus to spring 49 serves to urge centering of thegimbal cage and also as a load factor against which the inertia of thespinning gyro wheel can be caused to operate.

Secured in the lower end of casing 23 are operational means .adapted tobe coupled to the sensing device so as to be driven thereby forselective operation of control surfaces of the aircraft. In thepreferred embodiment here shown the operational means comprises an airvalve assembly which includes a valve body 70 which is upwardly open andsubstantially dish-shaped with a flat bottom 71 and an upstandingperipheral wall 72. A valve body cover 73 is fixed to the upper edge ofvalve body wall 72 and covers the upwardly open portion of the body, anda valve rotor 75 is rotatably mounted in the valve body and below cover'73. Rotor 75 closely fits the interior of wall 72. The operationalmeans comprising valve body 70, cover 73 and rotor 75, are mounted tothe lower end of casing 23, as by a mounting ring 77, secured inposition by a retainer ring 79.

Valve body 70 is held against rotation and other undesired movement by alink 81 which is secured at one end to the valve body bottom 71 and atits other end is secured to casing 23. It will be understood that thelink 81 may be adjusted so as to permit shift of position of 1 the valvebody as desired, but that in normal operation of the device the link istightly held in place in order to hold the valve body against undesiredrelative rotation.

Cover 73 is provided with an arcuate slo-t'83 which opens intocommunication with an aperture 85 in rotor 75, aperture 85 extendingperpendicularly of the rotor. Connected to the lower end of drive pin 69is a crank pin 87 which is preferably provided with a fork 89 at itsupper end by which it is connected to drive pin 69 and which gives alimited-1y hinged connection between the two elements to accommodate anypossible drag in movement therebetween. Crank pin 87 extends downwardlyfrom its fork connection to the drive pin through arcuate slot 83 andinto rotor aperture 85, snugly engaging therein so that upon rotation ofplate 43 under turning of gimbal cage 35 rotation of valve rotor 75 isaccomplished.

Valve body bottom 71 is provided with a pair of substantially parallelair passages 91, 93, which extend substantial-ly equidistantly alongopposite sides of the center of the valve and spaced substantiallyoutwardly therefrom. At one end air passage 91 communicates with a port95 formed in and extending upwardly into valve body wall 72 intermediatethe depth of the valve body wall. Port 95 extends downwardly throughvalve body bottom 71 and connects to a tube 97 extending below thesensing unit and being open to atmospheric pressure.

At its opposite end passage 91 communicates into an upwardly extendingbranch 98, which extends upwardly into wall 72 to a distanceintermediate the depth of the wall and substantially equal to the upwardextension of port 95 into the wall. Each of port 95 and branch 98 areadditionally connected through the interior of wall 72, thusestablishing communication to atmosphere into the interior of valve body70 adjacent the upper end of port 95 and adjacent the upper end ofbranch 98.

Passage 93 is provided at one end with a port 99, port 99 beingpreferably substantially diametrically opposite to port 95. Port 99extends upwardly into the wall 72 of the valve body intermediate thedepth of the wall and a distance substantially equal to the extensionthereinto of port 95 and branch 98. Port 99 further extends downwardlythrough and below bottom 71 of valve body 70 and at its lower endcommunicates with a tube 101 which is connected to vacuum source 65. Atits opposite end passage 93 is provided with an upwardly extendingbranch 102 which extends upwardly into wall 72 a substantially equaldistance intermediate the depth of wall 72. Both port 99 and branch 102are inwardly communicated through wall 72 to the interior of the valvebody. Thus there is established communication with the interior of thevalve body to vacuum source 65 at the upper extreini ties of port 99 andbranch 102.

Valve body 70 is provided with two additional ports 104, 106, whichextend upwardly into wall 72 to a distance intermediate the depth of thewall substantially equal to the extension thereinto of ports 95, 99, andbranches 98, 102. Each of ports 104, 106 extends downwardly throughbottom 71 of valve body 70 and into port 104 is fitted a tube 107 bywhich port 104 is connected to a servo unit 109. Similarly a tube 111 isconnected into port 106 and communicates that port with another servounit 113.

Each of ports 104, 106 adjacent their upper ends at the intermediatelevel of the valve body are communicated into the interior of the valvebody, thus establishing communication between the respective servos 109,113, and the interior of valve body 70. Each of servo 109, '113 isschematically shown in 'FIG. 1 of 'the drawings and is preferably of thevacuum operated diaphragm type, and the servos are respectivelyconnected as by cables 115, 117 to the aircraft control surfacerepresented by an elevator 109. Ports 104, 106 are diametrically opposedand are disposed on an axial line lying intermediate and substantiallyequidistant from passages 91, 93.

Valve rotor 75 is rotatably supported within the valve body betweenvalve cover 73 and valve body bottom '71. Rotor 75 in its periphery andat a height substantially equal to the positioning of the upper ends ofports 95, 99, 104, 106 and branches 98, 102, is provided with armatechannels 121, 123. Each of the channels is adapted to controlintercommunication between the ports and branches formed in valve bodywall 72. Thus in at rest position channel 121 is in direct communicationwith port 106. As shown in FIGS. 8 and 9, channel 121 terminatesadjacent port 95 at one end and branch 102 at its opposite 'end,although not in communication with either port 95 or branch 102.Simulaneously channel 123 communicates with port 104 and is out ofcommunication with port 99 and branch 98. Thus in at rest position bothof the servos 109, 113 are at rest. As can readily be seen, upon shiftof the position of valve rotor 75, intercommunication among the portsand branches and their respective outlets is effected and controlled.

Such change of position of the valve rotor is effected by turning ofplate '43 under the precessional rotation of the gimbal cage pursuant toprecession of the gyro wheel on change of attitude.

In order further to control and complete the proper operation of thepresent device a weight 125 is connected to the lower side of plate '43.Weight 125 is preferably substantially arcuate in cross section andextends substantially below plate 43 into adjacency with the cover 73 ofthe valve. Weight 125 partially surrounds drive pin 69 and crank pin 87,and is disposed radially outward from the gimbal axis defined by thepivots 36-, 37, with the vertical center of weight 125 being disposed ina plane which perpendicularly intersects the gyro spin axis, issubstantially parallel to the gyro wheel and to the gimbal axis so thatweight 125 is disposed eccentrically with relation to the gimbal cage.Weight'125 is also positioned adjacent the periphery of plate 43 so asto be at extreme radial distance from the gimbal axis. Weight 125, beingdisposed off-center from the gimbal axis, shifts under the influence ofgravity when a tilt develops in the attitude of the aircraft, the shiftof the weight under such tilt urging movement of the gimbal cage towhich the weight is connected in the direction of the precessionalrotation of the gimbal cage initiated by the torque force of tiltingmovement of the aircraft.

When the device is installed in an arioraft it is disposed so thatcasing 23 is positioned substantially up right with the spin axis ofgyro wheel 31 alined in parallelism with the longitudinal axis of theaircraft, and with the gimbal axis as defined by pivots 36, 37 disposedsubstantially perpendicularly to the spin axis of the gyro wheel andperpendicularly to the longitudinal axis of the aircraft. With thedevice thus disposed, plate 46 is positioned substantially parallel tothe longitudinal axis of the aircraft and to the spin axis of the gyrowheel, and weight *125 is maintained in balance. Spring 49 serves tourge the retention of the gimbal cage is substantially centeredposition.

With the device thus mounted line 63 may be connected to vacuum source 65 in order to provide for drive of the gyro wheel. Tube 101 may beconnected also to vacuum source 65 in order to provide a source ofvacuum into the interior of the device, and tubes 107, 111 mayrespectively be connected to servo units 109, 113 in order to providefor the vacuum operation of the servo units under manipulation of thedevice pursuant to change in attitude of the aircraft. So long as thelongitudinal axis of the aircraft remains parallel with itspredetermined angle of flight the device remains in balance and noactuation is effected upon the instrumentalities connected therewith. Insuch attitude the air valve is in the position as best shown in FIGS. 8and 9.

When, however, the aircraft deviates from the line of flight along itslongitudinal axis the curvature, whether of decline or incline, impartsa torque force to the gyro wheel 31, the axis of which force isperpendicular to the spin .axis of the gyro wheel, and also isperpendicular to the rotational axis of the gimbal cage, such torqueforce causing the gyro wheel to precess, effecting a movement thereofabout the gimbal cage axis moving the gimbal cage therewith, andconsequently moving plate 43 and the drive pin and crank pin connectedthereto at the same time.

Thus for example, if the aircraft goes into a flight line of curvatureupwardly from the original longitudinal axis of the aircraft, theprecession of the gyro moves to effect shift of the valve rotor 75 froma position as shown in FIGS. 8 and 9 toward a position as shown in FIG.10 of the drawings. When the valve rotor has moved in this mannerchannel .121 has shifted so as to establish communication between port106 and branch .102 so as to communicate vacuum from vacuum source 65through passage 93 and thence through line 111 to servo 11 3.Simultaneously channel 123 is shifted to communicate branch 9-8 withport 104 and to establish communication through passage '91 of servo 109with atmosphere. When these shifts have been accomplished the actions ofthe servos are such that the vacuum force applied to servo 113 operatesthe diaphragm therein efiecting operation of elevator 119 through cable117 and with the opposite servo 109 under the influence of atmosphereyielding to that movement, thus effecting an adjusting movement ofelevator 119 so as to urge correction of the attitude of the aircraft.

This correction, however, is not sufficient to solve the problem that ishere present, since upon curing of curvature in the line of flight, thetorque force applied to the gyroscope would be eliminated and thedemands of the gyroscope would thus be satisfied when the aircraft hadreturned to a straight line of flight without curvature. This merereturning to a straight line of flight does not fully correct theattitude of the aircraft since the aircraft may fly in a straight lineon a decline or on an incline, and yet the gyroscope will have no meansof itself for returning the aircraft not only to straight flight butalso to level flight.

Aoording-ly weight plays its important part simultaneously with thepreeessing. operation of the gyroscope under the torque force ofcurvature in flight. As has been pointed out weight 125 is disposed onplate 43 eccentrically of the gimbal axis, and when the attitude of theaircraft departs from level flight gravitational force urges weight 125to move in the direction of tilt of the aircraft. The movement of weight125 under tilt attitude of the aircraft moves the weight in thedirection of the precessional rotation of the gimbal cage, and theweight continues to unbalance the gyroscope so long as the attitude ofthe aircraft is at either an incline or decline position, thus causingthe valve rotor to be maintained in operational communication with theservos and thus with the control surfaces until the attitude of theaircraft has returned to level flight where weight 125 will resume abalance position. In this manner the aircraft is not only returned tostraight flight, but also is returned to level flight in a smooth actionwithout involving undue oscillation of the aircraft in achieving returnto corrected flight attitude. When the aircraft has returned to normalposition the gyro wheel and gimbal cage will have returned to normalposition, and valve rotor 75 returned to the position as shown in FIGS.8 and 9 of the drawings, reestablishing balance to both of the servosand interrupting operation of the elevator.

It will readily be understood that the present structure and thecontrols effected thereby may easily be overcome by manual controls asdesired in the operation of the aircraft, and as can be seen the presentdevice provides a simple and economical means automatically toeflectcorrection in the pitch attitude of aircraft giving a satisfactorypitchcon-trol of an automatic nature and of smooth and certain operationto return the aircraft not only to a straight line of flight but also toa level line of flight.

It will further be observed and understood that, while the specificoperational control has been herein shown and described in detail withrelation to the air valve, other types of rotational controls mayreadily be coupled for drive by and pursuant to rotational movement ofthe gimbal cage. Thus it is readily apparent that suitable electric orelectronic controls may be coupled and mounted for selective operationpursuant to gimbal cage movement and responsive to which operation ofthe elevator may be accomplished. It will be understood that, Whileweight 125 is shown and described specifically as mounted upon plate 43,the weight may be otherwise connected to gimbal cage 35, as for example,by direct attachment to the gimbal cage. In order to effect operationalmovement under tilt of the aircraft the weight should be offset from theaxis of the gimbal and the size and shape of theweight may be varied andadjusted as different types of conditions arise.

It further iVViH be seen that the operational controls may be directlyconnected to the gimbal cage, eliminating the interposition of theadditional connection means shown herein.

I claim:

1. In an aircraft having control surfaces for effecting pitch movementabout the transverse axis of the aircraft, pitch control means includinga gyroscope comprising a gimbal cage pivotally supported with its axisof pivot substantially perpendicular to the longitudinal axis of saidaircraft, a gyro wheel spinningly mounted in said gimbal cage with itsaxis of spin substantially parallel to said aircraft longitudinal axis,a plate fixed to said gimbal cage for pivoting therewith, said platebeing substantially parallel to said aircraft longitudinal axis, pinmeans connected to and depending below said plate disposed radiallyoutward from said gimbal pivot axis along a radius of said plate which isubstantially parallel to said aircraft transverse axis, Weight meansconnected to said plate radially outward from said pivot axis and saidpin means, the vertical center line of said weight means I disposedsubstantially on said plate radius whereby tilt of said plate responsiveto pitch tilt of said aircraft urges said weight to move around saidpivot axis under the force of gravity, said pitch tilt causingprecession of said gyroscope in the direction of weight movement,

. operational means drivenly coupled to said pin means,

said operational means comprising an air valve including a rotatablerotor parallel to said plate, vacuum operated means communicated withsaid air valve and connected to said control surfaces, a source ofvacuum communicated to said air valve, rotation of said rotorrespectively effecting communication of said vacuum operated means withsaid source of vacuum to operate said control surfaces and correct pitchcurvature of said aircraft, movement of said operational means rotorthereby correcting flight curvature and said weight continuing suchmovement to effect correction of flight level.

2. In an aircraft having control surface for effecting pitch movementabout the transverse axis of the aircraft,-pitch control means includinga gyroscope comprising a gimbal cage pivotally supported with its axisof pivot substantially perpendicular to the longitudinal axis of saidaircraft, a gyro wheel spinningly mounted in said gimbal cage with itsaxis of spin substantially parallel to said aircraft longitudinal axis,a plate fixed to said gimbal cage for pivoting therewith, said platebeing substantially parallel to said aircraft longitudinal axis, pinmeans connected to and depending below said plate disposed radiallyoutward from said gimbal pivot axis along a radius of said plate whichis substantially parallel to said aircraft transverse axis, Weight meansconnected to said plate radially outward from said pivot axis and saidpin means, the vertical center line of said weight means disposedsubstantially on said plate radius whereby tilt of said plate responsiveto pitch tilt of said aircraft urges said weight to move around saidpivot axis under the force of gravity, said pitch tilt causingprecession of said gyroscope in the direction of Weight movement,operational mean drivenly coupled to said pin means, said operationalmeans including a rotatable rotor parallel to said plate, vacuumoperated means communicated with said rotor and connected to saidcontrol surfaces, a source of vacuumcommunicated to said rotor, rotationof said rotor respectively effecting communicatin of said vacuumoperated means with said source of vacuum to operate said controlsurfaces and correct pitch curvature of said aircraft, movement of saidoperational means rotor thereby correcting flight curvature and saidweight continuing such movement to effect correction of flight level.

3. In an aircraft having control surfaces for effecting pitch movementabout the transverse axis of the aircraft, pitch control means includinga gyroscope comprising a gimbal cage pivotally supported with its axisof pivot substantially perpendicular to the longitudinal axis of saidaircraft, a gyro wheel spinningly mounted in said gimbal cage with itsaxis of spin substantially parallel to said aircraft longitudinal axis,a plate fixed to said gimbal cage for pivoting therewith, said platebeing substantially parallel to said aircraft longitudinal axis, weightmeans connected to and depending below said plate disposed radiallyoutward from said gimbal pivot axis with the vertical center of saidweight means along a radius of said plate which is substantiallyparallel to said aircraft transverse axis, whereby tilt of said plateresponsive to pitch tilt of said aircraft urges said Weight to movearound said pivot axis under the force of gravity, said pitch tiltcausing precession of said gyroscope in the direction of weightmovement, operational means drivenly coupled to said plate, saidoperational means including a rotatable rotor parallel to said plate,vacuum operated means communicted with said rotor and connected to saidcontrol surfaces, a source of vacuum communicated to said rotor,rotation of said rotor respectively effecting communication of saidvacuum operated means with said source of vacuum to operate said controlsurfaces and correct pitch curvature of said aircraft, movement of saidoperational means rotor thereby correcting flight curvature and saidweight continuing such movement to effect correction of fiight level.

4. In an aircraft having control surfaces for effecting pitch movementabout the transverse axis of the aircraft, pitch control means includinga gyroscope comprising a gimbal cage pivotally supported with its axisof pivot substantially perpendicular to the longitudinal axis of saidaircraft, a gyro wheel spinningly mounted in said gimbal cage with itsaxis of spin substantially parallel to said aircraft longitudinal axis,a plate fixed to said gimbal cage for pivoting therewith, said platebeing substantially parallel to said aircraft longitudinal axis, pinmeans connected to and depending below said plate disposed radiallyoutward from said gimbal pivot axis, weight means connected to saidplate radially outward from said pivot axis and said pin means, wherebytilt of said plate responsive to pitch tilt of said aircraft urges saidweight to move around said pivot axis under the force of gravity, saidpitch tilt causing precession of said gyroscope in the direction ofweight movement, operational means drivenly coupled to said pin means,said operational means comprising an air valve including a rotatablerotor parallel to said plate, vacuum operated means communicated withsaid ,air valve and connected to said control surfaces, a source ofvacuum communicated to said air valve, rotation of said rotorrespectively effecting communication of said vacuum operated means withsaid source of vacuum to operate said control surfaces and correct pitchtilt of said aircraft, movement of said operational means rotor therebycorrecting flight curvature and said weight continuing such movement toeffect correction of flight level.

5. In an aircraft having control surfaces for effecting pitch movementabout the transverse axis of the aircraft, pitch control means includinga gyroscope comprising a gimbal cage pivotally supported with its axisof pivot substantially perpendicular to the longitudinal axis of saidaircraft, a gyro wheel spinningly mounted in said gimbal cage with itsaxis of spin substantially parallel to said aircraft longitudinal axis,weight means connected to said gimbal cage radially outward from saidpivot axis, whereby tilt of said aircraft urges said weight to movearound said pivot axis under the force of gravity, said pitch tiltcausing precession of said gyroscope in the direction of weightmovement, operational means drivenly coupled to said gimbal cage, saidoperational means including a rotatable rotor, control manipulatingmeans communicated with said rotor and connected to said controlsurfaces, rotation of said rotor selectively effecting operation of saidcontrol manipulating means to operate said control surfaces and correctpitch tilt of said aircraft, movement of said operational means rotorthereby correcting flight curvature and said weight continuing suchmovement to effect correction of flight level.

6. In combination with an aircraft, a pitch control having a gyroscopewith a gimbal ring having a rotor mounted therein, said gimbal ringbeing mounted to pivot about an axis perpendicular to the longitudinalaxis of the aircraft, and gravity responsive means connected to saidgimbal ring causing movement of said gimbal ring about said gimbal ringaxis responsive to changing pitch attitude of said aircraft.

7. In combination with an aircraft, a pitch control having a gyroscopewith a gimbal ring having a rotor mounted therein, said gimbal ringbeing mounted to pivot about an axis perpendicular to the longitudinalaxis of the aircraft, a centralizing spring engaging said gimbal ringand urging it to assume a definite angular position about said gimbalring axis, gravity responsive means unbalancing said gimbal ring aboutsaid gimbal ring axis except when said aircraft is in normal flight,whereby change in pitch attitude of said aircraft will cause movement ofsaid gimbal ring about said gimbal ring axis.

8. In an aircraft having control surfaces for effecting pitch movementabout the transverse axis of the aircraft, pitch control means includinga gyroscope comprising a gimbal cage pivotally supported with its axisof pivot substantially perpendicular to the longitudinal axis of saidaircraft, a gyro wheel spinningly mounted in said gimbal cage with itsaxis of spin substantially parallel to said aircraft longitudinal axis,weight means connected to said gimbal cage radially outward from saidpivot axis, whereby tilt of said aircraft urges said weight to movearound said pivot axis under the force of gravity, said pitch tiltcausing precession of said gyroscope in the direction of weightmovement, operational means drivenly coupled to said gimbal cage andconnected to said control surfaces, movement of said operational meansthereby correcting I0 flight curvature and said weight continuing suchmovement to effect correction of flight level.

9. In combination with an aircraft, a pitch control having a gyroscopewith a gimbal ring having a rotor mounted therein, said gimbal ringbeing mounted to pivot about an axis perpendicular to the longitudinalaxis of the aircraft, a centralizing spring engaging said gimbal ringand urging it to assume a definite angular posit-ion about said gimbalring axis, weight means connected to said gimbal ring and unbalancingsaid gimbal ring about said gimbal ring axis except when said aircraftis in normal flight, whereby change in pitch attitude of said aircraftwill cause movement of said gimbal ring about said gimbal ring axis.

10. In combination with an aircraft, a pitch control having a gyroscopewith a gimbal ring having a rotor mounted therein, said gimbal ringbeing mounted to pivot about an axis perpendicular to the longitudinalaxis of the aircraft, a centralizing spring engaging said gimbal ringand urging it to assume a definite angular position about said gimbalring axis, weight means connected to said gimbal ring eccentrically ofsaid gimbal ring axis unbalancing said gimbal ring about said gimbalring axis except when said aircraft is in normal flight, whereby changein pitch attitude of said aircraft will cause movement of said gimbalring about said gimbal ring axis.

11. In an aircraft having control surfaces for effecting pitch movementabout the transverse axis of the aircraft, pitch control means includinga gyroscope comprising a gimbal cage pivotally supported with its axisof pivot substantially perpendicular to the longitudinal axis of saidaircraft, a gyro wheel spinningly mounted in said gimbal cage with itsaxis of spin substantially parallel to said aircraft longitudinal axis,gravity responsive means connected to and unbalancing said gimbal cage,whereby tilt of said aircraft urges said gravity responsive means tomove around said pivot axis under the force of gravity, said pitch tiltcausing precesSing of the gyroscope in the direction of gravityresponsive means movement, operational means drivingly coupled to saidgimbal cage and connected to said control means thereby correctingflight curvature and said gravity responsive means continuing suchmovement to effect correction of flight level.

References Cited by the Examiner UNITED STATES PATENTS 1,592,081 7/1926Colvin 74-5 X 2,199,256 4/1940 De Florez 244-79 2,579,570 12/1951Hauptman 244 79 3,006,580 10/1961 Clarkson 24478 FOREIGN PATENTS 587,8975/1947 Great Britain.

MILTON BUCHLER, Primary Examiner.

A. H. FARRELL, Assistant Examiner.

1. IN AN AIRCRAFT HAVING CONTROL SURFACES FOR EFFECTING PITCH MOVEMENTABOUT THE TRANSVERSE AXIS OF THE AIRCRAFT, PITCH CONTROL MEANS,INCLUDING A GYROSCOPE COMPRISING A GIMBAL CAGE PIVOTALLY SUPPORTED WITHITS AXIS OF PIVOT SUBSTANTIALLY PERPENDICULAR TO THE LONGITUDINAL AXISOF SAID AIRCRAFT, A GYRO WHEEL SPINNINGLY MOUNTED IN SAID GIMBAL CAGEWITH ITS AXIS OF SPIN SUBSTANTIALLY PARALLEL TO SAID AIRCRAFTLONGITUDINAL AXIS, A PLATE FIXED TO SAID GIMBAL CAGE FOR PIVOTINGTHEREWITH, SAID PLATE BEING SUBSTANTIALLY PARALLEL TO SAID AIRCRAFTLONGITUDINAL AXIS, PIN MEANS CONNECTED TO AND DEPDNING BELOW SAID PLATEDUSPOSED RADIALLY OUTWARD FROM SAID GIMBAL PIVOT AXIS ALONG A RADIUS OFSAID PLATE WHICH IS SUBSTANTIALLY PARALLEL TO SAID AIRCRAFT TRANSVERSEAXIS, WEIGHT MEANS CONNECTED TO SAID PLATE RADIALLY OUTWARD FROM SAIDPIVOT AXIS AND SAID PIN MEANS ,THE VERTICAL CENTER LINE OF SAID WEIGHTMEANS DISPOSED SUBSTANTIALLY ON SAID PLATE RADIUS WHEREBY AND OF SAIDPLATE RESPONSIVE TO PITCH TILT OF SAID AIRCRAFT URGES SAID SEIGHT TOMOVE AROUND SAID PIVOT AXIS UNDER THE FORCE OF GRAVITY, SAID PITCH TILTCAUSING PRECESSION OF SAID GYROSCOPE IN THE DIRECTION OF WEIGHTMOVEMENT, OPERATIONAL MEANS DRIVENLY COUPLED TO SAID PIN MEANS SAIDOPERATIONAL MEANS COMPRISING AN AIR VALVE INCLUDING A ROTATABLE ROTORPARALLE OT SAID PLATE, VACUUM OPERATED MEANS COMMUNICATED WITH SAID AIRVALVE AND CONNECTED TO SAID CONTROL SURFACES, A SOURCE OF VACUUMCOMMUNICATED TO SAID AIR VALVE, ROTATION OF SAID ROTOR RESPECTIVELYEFFECTING COMMUNICATION OF SAID VACUUM OPERATED MEANS WITH SAID SOURCEOF VACUUM TO OPERATE SAID CONTROL SURFACES AND CORRECT PITCH CURVATUREOF SAID AIRCRAFT MOVEMENT OF SAID OPERATIONAL MEANS ROTOR THEREBYCORRECTING FLIGHT CURVATURE AND SAID WEIGHT CONTINUING SUCH MOVEMENT TOEFFECT CORRECTION OF FLIGHT LEVEL.